Stacker assembly for corrugated sheets and the like

ABSTRACT

An improved stacker assembly including an oscillating squaring bar and control means therefor for achieving an improved orientation of stacked sheets to assure perfect lead edge alignment thereof, while enabling the stacked sheets to be readily removed without interference from the squaring means. The squaring bar is cyclically engaged with the trailing edges of sheets disposed on a storage table to urge the lead edges of the sheets against an alignment bar disposed downstream therefrom, the control means assuring that the squaring bar will be spaced from the trailing edges of the sheets when operation of the apparatus is interrupted for lateral unloading of the formed stacks.

.nited States Patent 1191 Lopez 1541 STACKER ASSEMBLY FO CORRUGATED SHEETS AND THE LIKE [75] Inventor: John Lopez, Westfield, NJ.

{73] Assignee: Koppers Company, Inc., Pittsburgh,

22] Filed: Feb.7, 1972 211 Appl. No.; 224,050

Related US. Application Data [63] Continuation-impart 6r Ser. N0. 186,310, Oct. 4,

s2 U.S. c1. .214/6 s, 2l4/60, 271/89 51 Int. Cl ..B65g 57/09 [58 Field of Search ..2l4l6 D, 6 H,6 s; 271/88, 271/89 56 References Cited UNITED STATES PATENTS 2,657,052 10 1953 E1110: .27l/89 x 1 Jan. 23, 1973 2/1963 Lopez ..2l4/6 D X 3,079,150 3,382,966 5/1968 Califano et al ..2l4/6 D x 3,463,485 8/1969 Atwood ..27l/89 Primary Examiner-Robert J. Spar AttorneyA1'thur B. Colvin [57] ABSTRACT An improved stacker assembly including an oscillating squaring bar and control means therefor for achieving an improved orientation of stacked sheets to assure perfect lead edge alignment thereof, while enabling the stacked sheets to be readily removed without interference from the squaring means.

The squaring bar is cyclically engaged with the trailing edges of sheets disposed on a storage table to urge the lead edges of the sheets against an alignment bar disposed downstream therefrom, the control means assuring that the squaring bar will be spaced from the trailing edges of the sheets when operation of the apparatus is interrupted for lateral unloading of the formed stacks.

5 Claims, 5 Drawing Figures PATENIEDJAH 23 ms SHEET 3 BF 5 PATENIEBJAHZS m5 3.712.486

' saw 0F 5 STACKER ASSEMBLY FOR CORRUGATED SHEETS AND THE LIKE CROSS-REFERENCE This application is a continuation in part of application, Ser. No. 186,310, filed Oct. 4, 1971, entitled Stacker Apparatus For Multiple Corrugated Sheets.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is in the field of stacking apparatus, and more particularly is directed to the formation of stacks of relatively rigid sheets of material, as

exemplified by corrugated cardboard box blanks or sheets.

Corrugated cardboard material of the type employed for the formation of boxes and the like is typically produced in wide bands or sheets which are longitu dinally advanced through a slitting apparatus which forms two or more elongated webs from the sheets, the

, widthwise dimension of the webs being predetermined in accordance with the desired dimensions of the box blanks. The webs are thereafter chopped into suitable lengths, the multiple individual sheets or box blanks thus produced being progressively advanced and formed into stacks containing a desired number of blanks. The stacks are thereafter stored for subsequent processing, or are fed to subsequent fabricating stations for printing, gluing, etc.

Corrugated material, especially after the same is slit and chopped, displays asubstantial tendency to warp posed sheets onthe interleaved sheet may seriously I complicate separation of the stacks.

In view of the warpage tendency previously alluded to, conventional feeding and squaring apparatuses may be unsuitable for use with corrugated sheets, and conventional feeding and stack forming solutions, when applied to corrugated sheets, may be totally unsuitable.

2.The Prior Art 2 The above noted copending application represents a substantial advance in the formation of stacks of corrugated sheets. In said application, a plurality of side-byside disposed groupsor streams of sheets are fed to a slowdown conveyor, which functions to shingle the sheets, i.e.- to overlap upstream disposed sheets over downstream sheets. Thesheets are thereafter longitudinally advanced onto a storage or stack formation table.

The stack formation table is providedwith an alignment bar for engaging the lead edges of the sheets and a squaring belt assembly which overlies the sheets on the storage table. The squaring belt assembly frictionally engages the upper surfaces of the sheets, yieldingly forcing the lead edges of the latter against the alignment bar so as to square the sheets and minimize any tendency toward interleaving of adjacent stacks of sheets. After a predetermined number of sheets are stacked, the squaring assembly is cleared from the uppermost sheets and the separate stacks may thereupon be removed from the storage table to a lateral take-off conveyor for further processing.

Although the device of the above mentioned pending application significantly reduces the possibility of formation of improper stacks, there has been observed, due to the unusual characteristics of corrugated sheets above referred to, a continued but lessened tendency for the formation of stacks including skewed or disarrayed sheets.

Moreover, in processing sheets of considerable length in which the spacing between the squaring bar on the storage table and the in-feed mechanism must necessarily be substantial, it has been observed that certain sheets may not be fed to the squaring belt assembly and, thus, the beneficial effects of such squaring belt are lost in respect of such sheets.

SUMMARY OF THE INVENTION The present invention may be summarized as including, in combination with a device of the type described, an oscillating squaring blade mechanism which, during the feed of sheets to the storage table, is cyclically engaged against the trailing edges of corrugated sheets on such table, the spacing and travel of such squaring blade being adjusted and arranged relative to the alignment bar in such manner as to press the lead edges of the sheets against the alignment bar.

Control apparatus is provided which assures that upon completion of the formation of a series of stacks of sheets, operation of the oscillating bar will be discontinued. Upon interruption of operation of the oscillating bar, the control apparatus assures that the bar will be spaced from the trailing edges of such sheets, whereby the bar does not impede lateral removal of the stacks. I v The oscillating squaring bar assembly performs the additional function, where used in conjunction with the squaring belt assembly previously described, of assuring that all sheets are advanced into the influence of the squaring belt assembly.

It is accordingly an object of the invention to provide an improved stacker apparatus particularly adapted for the formation of perfect stacks of rigid sheets, such as corrugated cardboard sheets, which, due to their special characteristics, cannot be processed by conventional handling equipment. A further object of the invention is the provision of an apparatus of the type described having especial utility when used in conjunction with the squaring belt assembly of the above referred to pending application, characterized by the incorporation therein of control mechanism which assures that the oscillating bar assembly, after completion of formation of the stacks, will bewithdrawn from the trailing edges of the sheets, and, thus, will not impede the removal of the stacks onto a lateral take-off conveyor.

A further object of the invention'is the provision of an apparatus of the type described including a novel infeed assembly which assures that the sheets are advanced at all times at an optimal speed.

To attain these objects and such further objects as may appear herein or be hereinafter pointed out,

reference is made to the accompanying drawings, forming a part hereof, in which:

FIG. 1 is a perspective view of a feed and stacker assembly for corrugated sheets, incorporating the improvements of the present invention;

FIG. 2 is a magnified perspective view of the oscillating bar and control components in accordance with the present invention;

FIG. 3 is a magnified vertical section taken on the line 3-3 of FIG. 1;

FIG. 4 is a section taken on the line 4-4 of FIG. 3;

FIG. 5 is a further magnified vertical section taken on the line 5-5 of FIG. 4.

Referring now to the drawings, there is shown in FIG. 1 an over-all perspective view of apparatus for completing the formation of stacks of corrugated cardboard sheets or box blanks. It will be understood that the sheets or blanks, after stacking, will be removed and transported to remote zones for such further operations as may be required for completion of the blanks.

Generally, the apparatus includes a supply zone which provides a source of blanks or sheets which have been severed from the web. Blanks are advanced at high speed to a slow-down conveyor zone 11 wherein the linear speed of the sheets is reduced as contrasted with zone 10, resulting in a shingling or partial overlapping of the sheets on the slow-down conveyor. The slow-down or supply conveyor, as it is hereinafter interchangeably referred to, moves the shingled sheets to an in-feed assembly 12 which functions to accelerate the sheets and dispose the same on a sheet receiver table 13.

The lead edges of the sheets or box blanks B are, in the manner hereinafter more fully set forth, pressed against an alignment bar assembly 14 by apparatus to be discussed in further detail. In the illustrated embodiment of the invention, it will be apparent that two discrete stacks of side-by-side disposed blanks B are simultaneously formed against the alignment bar assembly. It will, however, be appreciated that the apparatus is capable of simultaneously processing more than two stacks and, alternatively, can be used, if

desired, to form only a single stack.

Interposed between the supply conveyor 11 and the in-feed assembly 12, there is provided a gate mechanism 15 which functions in a manner more fully set forth in the above referred to pending application, temporarily to interrupt the advance of shingled sheets to the in-feed assembly, while permitting an accumulation of sheets against the gate member during the period when completed stacks of sheets are being removed from the receiver table 13.

A right angle take-off conveyor assembly 16 is positioned to receive the completed stacks disposed adjacent the alignment bar 14. Optionally but preferably, an auxiliary feed and alignment assembly 17, illustrated in FIG. 1 as constituting the squaring belt assembly described and claimed in the noted pending application, is disposed in position to engage the upper faces of sheets advanced by the in-feed assembly and press the lead edges of the latter against the alignment bar assembly 14.

The slow-down or supply conveyor 11 is provided with counting mechanism which functions to activate the gate 15 to prevent the continued feed of sheets to the in-feed assembly 12 after a predetermined number of sheets have been passed to the in-feed assembly.

The preceding discussion has been of a general nature sufficient merely to facilitate an understanding of the contributions of the present invention.

A principal advance of the present invention is considered to reside in the combination with the aforesaid apparatus of a reciprocating squaring bar apparatus, referred to generally as 18.

As best seen in FIGS. 2 and 3, the slow-down conveyor 11 includes a belt 19 on which the sheets are advanced, the belt being in driving connection with idler support roller 20, keyed to drive shaft 21, suitably journalled for rotation on the side frames 22 of the assembly.

The slow-down or supply conveyor 11 is preferably operating constantly, the speed of advance of the conveyor being varied by apparatus not pertinent to the present invention, in accordance with the position of the gate assembly 15. Where the gate assembly is positioned to interrupt movement between the conveyor 11 and in-feed assembly 12, the speed of advance of the belt 19, and hence, the rotational speed of the shaft 21, will be less than is the case where the gate is open and a free-flow connection between the supply conveyor and in-feed assembly is permitted.

The in-feed assembly, as best appreciated from a consideration of FIGS. 2 and 3, comprises a drive shaft 23 suitably joumalled on the side plates 22 of the apparatus, the shaft being rotatable about an axis parallel with the shaft 21. A plurality of spaced drive rollers 24 are mounted on the shaft 23 for rotation therewith. Blanks passing from the slow-down conveyor to the infeed assembly are received in the nip between the driving rollers 24 and idler rollers 25.

In accordance with the invention, the speed with which the rollers 24 are driven is controlled so as to be at least equal to, and preferably exceed, the speed of advance of the sheets on the slow down conveyor. To assure this result, and recalling that the speed of the slow-down conveyor will vary in accordance with the position of the gate assembly 15, there will next be described a drive assembly whereby the shaft 23 carrying the rollers 24, is driven by power derived from the slow-down conveyor when the same operates at full speed, or from an auxiliary power source when the speed of the slow-down conveyor is substantially reduced.

To this end, the shaft 23 carries a drive sprocket 26 which is connected by drive chain 27 to sprocket 28 keyed to drive sleeve 29. The sleeve 29 is rotatably mounted to stub shaft 30 fixed by a mounting boss 31 to a side plate 22 of the frame. Keyed to the sleeve 29 is a drive cam member 32 which includes diametrically opposed drive shoulders 33, 34, extending radially with respect to the axis of rotation of the sleeve 29, and ramp or sloped surfaces 35, 36 in the area between the shoulders 33,34.

A pair of sprocket members 37, 38 are rotatably mounted relative to the sleeve at opposite sides of the drive cam 32. The sprocket 37 is connected by chain 39 to an output sprocket 40 fixed to shaft 21 of the slow-down conveyor. The sprocket 38 is connected by drive chain 41 to a drive sprocket 42 fixed to shaft 43 of an auxiliary drive motor 44 which preferably incorporates an integral speed reducer.

It will thus be readily recognized that either of the two sprockets 37 or 38 may be independently rotated relative to the cam member 32 which is keyed to the sleeve 29. The sprockets 37, 38 are selectively connected to the cam 32 to provide motive power to the cam and, hence, to sleeve 29, in accordance with which said sprocket is rotated at a more rapid rate, by pawl mechanisms next to be described.

Sprocket 37 carries a pivotal pawl 45 which is yieldingly biased to. pivot in n anti-clockwise direction as viewed in FIG. 2, by a tension spring 46 interposed between the pawl 45 and a pin 47 fixed to the sprocket. In similar manner, the sprocket 38 carries a pivotal pawl 48 yieldingly biased to lie against the surface of the cam 32 by the spring 49 tensioned between the pawl 48 and an anchor pin 50.

From the foregoing description it will be evident that if the sprocket 37, driven by chain 39, is rotated at a more rapid rate than sprocket 38, driven by chain 41, the pawl 45 will be pressed against one of the seats 33 or 34 of the cam 32, whereby the cam and, accordingly, the sleeve will be driven at the same rotational speed as the sprocket 37. Since the cam is rotating at a more rapid rate than the sprocket 38, it will be evident that the pawl 48, which is mounted on the sprocket 38, will progressively ride over the inclined or ramp surfaces 35, 36, snapping back against the surface of the cam after passing over each of the drive shoulders 33 and If,- however, due to a reduction of speed of the slowdown conveyor which drives sprocket 37, the sprocket 37 is rotated at a speed less than the speed of rotation applied to sprocket 38 by motor 44, it will be apparent that the pawl 48 will provide the driving connection between sprocket 38 and cam 32, in which instance pawl 45, carried by the then slower moving sprocket 37, will merely be scanned against the surface of the cam.

- Squaring bar 18, in accordance with the instant invention, includes a transversely extending pusher member 51 which carries adjacent each marginal edge portion 52 a guide rod member 53. The guide rods 53 extend through guide bushings 54 made fast to the frame, the conjoint action of the shaft and bushings being such as to permit only a forward and rearward oscillating movement of the bar assembly 18. 7

It will be evident that, if desired,the positions of the bosses and rods may be reversed, with the guide rods fixed to the frame and the bosses secured to the assembly 18.

Motive power for inducing oscillatory movement of the bar 18is provided by a drive motor 55 fixed to the frame. The drive motor 55 includes a drive plate 56 having an eccentric drive pin 57 extending therefrom see FIG. 5. The drive pin 57 is pivotally connected to the drive link 58, the opposite end 59 of the link being disposed in the lower bifurcated end 60 of the drive lever 61. A clevis pin 62 extendsbetween thebifurcated leg portions 60 of the lever 61 pivotally through aperture 63 in the end 59 of the link 58.

The lever 61 is keyed at a central or fulcrum portion 64 to a rocker shaft 65journalled between the plates 22, it being evident from the preceding description that rotation of the motor 55 and drive plate 56 will induce a reciprocal partial rotation of the shaft 65.

The opposite end 66 of the lever 61 is likewise bifurcated and provided with aligned apertures 67 spanned by transverse pin 68. Operator link 69 is provided with a cross bore rotatably mounted over the pin 68. The other end 70 of the link 69 is pivotally connected by a pin 7l'to an aperture formed in a web 72 fixed, as by machine screws 73, to the pusher member 51.

It will be appreciated that although only a single lever assembly is shown in the illustrated embodiment of the invention, a plurality of such lever or rocker arm assemblies may be carried on the shaft 65 to act on the pusher member 51, to assure a uniform distribution of forces across the entire transverse extent of the pusher.

The pusher member 51 carries a plurality of upstanding pusher fingers 74, the fingers being bolted or otherwise made fast to the member 51. The fingers are arranged to lie between the drive rollers 24.

As best understood from a comparison of the dot and dash and solid line positions disclosed in FIG. 5, it will be seen that the reciprocal movement imparted to the pusher 51 by the rocker arm lever 61 is of a sufficient magnitude to enable the pusher to be extended beyond the leading edge of the drive rollers 24 on itsouter or extended stroke, and to be retracted into a position behind the said rollers (solid lines) on its retractile stroke.

Optionally but preferably, in order to compensate for any possible sagging :or departure from a purely horizontal movement of the squaring bar assembly 18, including the pusher bar and its associated mechanism, the frame portion 75 adjacent the input end of the support table 13 includes a transversely extending guide plate 76 having chamfered portions 77, 78 at its leading and trailing transverse margins.

As best seen in FIGS. 2 and 4, photo electric sensing mechanism 79 is provided which is responsive to and controls the position of the rocker arm 61 and, hence, the-squaring blade assembly 18. To this end, a right angle bracket 80 has its lower leg 81 made fast to the frame of the apparatus, the vertical leg 82 of the bracket carrying a photo electric cell 83. The oppositely positioned bracket 84 has its base leg 85 affixed to the frame, the vertical leg 86 of the bracket 84 being disposed opposite the vertical leg 82 of the bracket 80.

The photo electric sensing mechanism 83 includes a counterpart mechanism 87 carried on the leg 86 of the bracket 84 in such manner that interruption of a light beam extending precisely between the mechanisms 83 and -87 may be employed to activate a control apparatus, such as a relay or the like (not shown). It will be evident that the photo cell units may be of any selected conventional type, including, by way of example, a photo responsive element carried at 83 and a light source at 87, or both the .light source and the photo responsive device may be located at 83, with a planar or focusing mirror located at 87.

The lowermost end 60 of the rocker arm lever 61 carries a flag 88 positioned to interrupt the light beam between the previously described photosensitive devices when the rocker arm reaches a position at which the squaring bar assembly 18 achieves its maximum retracted position.

The gate assembly 15 forms no part of the present invention but will be described generally to facilitate an understanding of the operation of the apparatus.

It will be appreciated that the function of the gate as sembly is to permit a continued operation of the supply conveyor 11 during the period when stacks of blanks or sheets are being removed from storage table 13 to the take-off conveyor 16. During such period, it will be understood that the gate assembly 15 is in the lowered position shown in FIG. 3, at which position sheets will engage against the face portion 89 (FIG. 3) of the gate, the sheets being released when the gate is lifted for passage to the previously described in-feed assembly.

The gate assembly 15 includes a support structure 90, mounted for vertical shifting movement on spaced guide rods 91. To this end, a pair of bushings 92 having vertically oriented apertures slidably engage each side guide rod 91. A lift chain or chains 93, having the lowermost links mounted to the assembly 90, are reeved over sprockets (not shown) mounted on the super-structure. Physical lifting of the gate assembly is effected by means of an air cylinder or like apparatus which, acting through the chain, applies a lifting force to the end 93' thereof.

At 94 there is shown one of several detector rollers which are supported on detector levers 95 pivotally mounted to the gate assembly 90. The'levers, where multiple detectors are employed, are connected by a transversely extending detector bar 95 Each roller 94 is aligned in an opening between drive rollers 24. Chain member 96 is affixed to the detector bar 95', the upper end of the chain 96 being operatively connected to a microswitch member (not shown). It is the function of the detector assembly to sense the passage beyond the roller 94 of the last sheet or board in a group fed to the supply table.

It will be appreciated that the bar 95 is maintained in a first or relatively lifted pivoted position while a sheet is fed between drive rollers 24 and idler roller 25 see dot and dash positions, FIG. 5 and that when the sheet passes beyond all of the rollers 94, the bar is permitted to pivot downwardly, activating the microswitch.

As previously noted, the apparatus of the present invention is optionally but preferably employed in conjunction with a tuck-in roller assembly which aids in squaring blanks or sheets against the alignment bar 14.

The tuck-in assembly 17 includes a peripheral belt member 97 see FIG. 1 having a lowermost peripheral portion frictionally and yieldingly engaged against the uppermost surfaces of sheets as they are advanced beneath this portion. The tuck-in assembly 17 is mounted for pivotal movement about a horizontal axis, it being understood that as sheets accumulate on the table 13, the peripheral or sheet engaging portion of the belt 97 will be pivoted in an anti-clockwise direction as viewed in FIG. 1.

The tuck-in assembly functions to advance the sheets against the alignment bar 14 to facilitate the formation of neat stacks or groups of box blanks. Mechanism is provided for clearing the tuck-in assembly from the upper surface of the uppermost blank in the completely formed stacks so that this assembly will not interfere with the facile removal of completed stacks from the storage table 13 to the take-off conveyor 16.

The operation of the apparatus will be evident from the preceding description.

Box blanks B, slit and chopped to proper dimensions, are advanced in shingled array along the slow-down conveyor 11 to the in-feed assembly 12 defined by the drive rollers 24 and idler roller 25. The sheets are positively advanced by the aforementioned in-feed assembly along the table 13.

After passing clear of the nip between the rollers 24 and 25, the rear or trailing edges of the sheets fall to a position at which they are engaged by the cyclically moving oscillator bar 51. The oscillator bar, at its forward stroke, i.e. its stroke toward the alignment bar 14, aids in the alignment of the boards against the bar.

The bar 14, together with the tuck-in roller assembly 17, is lengthwisely adjustable along the table 13 to permit the same to be adapted for the feed of blanks of various lengths. In adjusting the position of the bar 14, care should be taken that the bar 14 is not in such close proximity to the oscillator bar 51 at the forwardmost limiting position of the stroke of the bar that the boards are compressed or crushed between the noted positions.

it will be appreciated that if, due to some mischance, a board is fed in skewed relation, the trailing edge of the board will be angularly oriented relative to the bar 51 so that, on its forward stroke, the bar will engage a corner only of the board. Due to the drag between the skewed board and the underlying supporting boards or sheets, the pressure of the oscillator bar 51 against a corner only of the fed board will be effective to straighten the latter such that the lead edge of the same will be squared or substantially squared as it comes beneath the tuck-in belt assembly 17. The conjoint action of the tuck-in assembly in squaring the lead edge against the alignment bar 14 and the continued straightening action by the oscillating bar against the trailing edge has been found effective in substantially all instances to achieve a corrective influence on an improperly fed blank.

When a selected number of blanks have been advanced by the conveyor 11, the gate mechanism 15 is lowered into a space between the stream of shingled sheets provided by the accelerating influence of the drive rollers 24. In the lowered position of the gate, the speed of the conveyor 11 is reduced, to effect an increased shingling or overlapping of the sheets and a permitted accumulation of the latter against the gate 15.

As previously noted, the driving force to the rollers 24 is normally provided by power take-off through the chain 39 driven by the conveyor 11. With the slow down of the conveyor 11, motive power is provided by the chain 41 since the sprocket 38 is driven at this time at a greater speed than the sprocket 37. Due to the continued rotation of the drive rollers 24, any sheets which have passed the gate mechanism will continue to be fed to a position over the supply table. When the trailing edge of the last such sheet passes beyond the detector rollers 94, such rollers will be permitted a degree of downward pivotal movement, which pivotal movement results in a downward movement of the detector bar and the chain 96, whereby the switch controlled by the chain will be deactivated.

The motor 55 which controls the reciprocation of the oscillator bar 51 is deactivated responsive to the simultaneous occurrence of two conditions, namely, a change of sense in the switch controlled by the chain 96, and an interruption of the light beam controlling the photo cell assembly 79 by the flag 88. As a result of the simultaneous occurrence of the two conditions, the movement of the oscillator bar 51 is stopped in precisely the completely retracted position thereof by deactivation of the motor 55, the latter being preferably provided with an automatic brake which inhibits further rotary movement of the drive plate 56 when the motor is deenergized.

It will thus be seen that after the last sheet is fed to the stack, the oscillator bar will be spaced a substantial distance from the trailing edges of the stack of sheets or blanks see FIG. 3, solid lines-, whereby the stack may be removed from the storage table without interference, such as would be experienced if the bar were pressed against the trailing faces of the sheets or spaced only a slight distance therefrom.

It will be understood that the lifting of the tuck-in assembly 17 is coordinated with the interruption of operation of the oscillator bar so that there is no interference by the tuck-in belt with the stacks. After the stack removal operation has been completed, the apparatus is recycled for continued feed of sheets to the supply table.

It will be appreciated that recycling may be manually initiated or may be automatically effected responsive to a predetermined timing cycle. Recycling, as will be understood, involves a lifting of the gate mechanism, whereupon sheets disposed against the gate will be permitted to advance into the influence of the drive rollers 24, from which position they will be fed to the supply table, etc. When the gate mechanism is lifted, the switch controlled by the chain 96 of the detector rollers 94 is reset to a condition at which it can", after the next lowering cycle of the gate, detect passage of the trailing edge of the last fed sheet of a succeeding stack.

From the foregoing it will be evident that there is described herein an improved stacking assembly incorporating an oscillator bar which functions to facilitate the alignment of sheets in stacks against the alignment bar. The device includes automatic control mechanism which assures that the oscillator bar will be in its retracted position during unloading of the apparatus, whereby the bar will not interfere with the unloading operation of the sheets or blanks. By incorporating in the stacker assembly a tuck-in belt mechanism, the conjoint squaring effects of the two components will be realized, the combination having the further advantage that the oscillating bar will assure that sheets which may be skewed to a substantial extent will nonetheless come under the influence of the tuck-in belt assembly.

The embodiment of the invention illustrated herein should not be construed in a limitative sense but, rather, the invention should be broadly construed within the scope of the appended claims.

Having thus described the invention and illustrated its use, what is claimed as new and is desired to be secured by Letters Pat. is:

l. A stacker device adapted to form a plurality of side-by-side disposed, lead edge aligned stacks of corrugated sheets comprising supply conveyor means for advancing a plurality of sheets in shingled array, an infeed assembly positioned to receive sheets from said supply conveyor means and advance the latter in a linear direction, gate means interposed between said conveyor means and in-feed assembly for blocking flow from said supply conveyor to said assembly responsive to the passage of a predetermined number of sheets over said supply conveyor, a sheet receiver table positioned to receive and support in stacked relation sheets advanced in said linear direction by said in-feed assembly, an alignment bar member extending transversely across said table normal to said linear direction, in spaced relation to said in-feed assembly, positioned to engage and align the lead edges of said sheets on said table, right angle take-off conveyor means adjacent said table for periodically receiving stacks of sheets disposed against said bar member and shifting the same in said transverse direction, squaring bar means adjacent said in-feed assembly, drive means for cyclically shifting'said bar means toward and away from said alignment bar member into intermittent contact with the trailing edges of the sheets on said table for urging the lead edges of the latter against said alignment bar member, and control means for deactivating said drive means of said squaring bar when the latter is in the away position, said control means including first switch means responsive to an absence of sheets in said in-feed assembly, and second switch means responsive to the position of said squaring bar 2. The combination of claim 1 wherein said second switch means includes a photo cell and light source, and said squaring bar is operatively connected to a flag member positioned to be interposed between said cell and light source in said away position.

3. The combination of claim 2 wherein said in-feed assembly comprises a series of laterally spaced apart drive rollers, and said squaring bar includes a plurality of vertically directed pusher fingers, said fingers lying in the spaces between said rollers in said away position.

4. The combination of claim 1 and including auxiliary feed means interposed between said in-feed assembly and said alignment bar for urging the uppermost sheet on said table toward said bar.

5. The combination of claim 1 including power transfer means comprising a first clutch element in driving connection with said infeed assembly, second and third clutch elements drivingly connected, respectively, to said supply conveyor and to a drive motor, and operator means operatively coupling said first clutch element automatically to the faster moving of said second or third clutch elements.

I 1: a ns t 

1. A stacker device adapted to form a plurality of side-by-side disposed, lead edge aligned stacks of corrugated sheets comprising supply conveyor means for advancing a plurality of sheets in shingled array, an in-feed assembly positioned to receive sheets from said supply conveyor means and advance the latter in a linear direction, gate means interposed between said conveyor means and in-feed assembly for blocking flow from said supply conveyor to said assembly responsive to the passage of a predetermined number of sheets over said supply conveyor, a sheet receiver table positioned to receive and support in stacked relation sheets advanced in said linear direction by said in-feed assembly, an alignment bar member extending transversely across said table normal to said linear direction, in spaced relation to said in-feed assembly, positioned to engage and align the lead edges of said sheets on said table, right angle take-off conveyor means adjacent said table for periodically receiving stacks of sheets disposed against said bar member and shifting the same in said transverse direction, squaring bar means adjacent said infeed assembly, drive means for cyclically shifting said bar means toward and away from said alignment bar member into intermittent contact with the trailing edges of the sheets on said table for urging the lead edges of the latter against said alignment bar meMber, and control means for deactivating said drive means of said squaring bar when the latter is in the away position, said control means including first switch means responsive to an absence of sheets in said in-feed assembly, and second switch means responsive to the position of said squaring bar
 2. The combination of claim 1 wherein said second switch means includes a photo cell and light source, and said squaring bar is operatively connected to a flag member positioned to be interposed between said cell and light source in said away position.
 3. The combination of claim 2 wherein said in-feed assembly comprises a series of laterally spaced apart drive rollers, and said squaring bar includes a plurality of vertically directed pusher fingers, said fingers lying in the spaces between said rollers in said away position.
 4. The combination of claim 1 and including auxiliary feed means interposed between said in-feed assembly and said alignment bar for urging the uppermost sheet on said table toward said bar.
 5. The combination of claim 1 including power transfer means comprising a first clutch element in driving connection with said infeed assembly, second and third clutch elements drivingly connected, respectively, to said supply conveyor and to a drive motor, and operator means operatively coupling said first clutch element automatically to the faster moving of said second or third clutch elements. 